I saw something on 60 minutes (I think) where they took water from a drinking fountain in Harlem, water from a hose, water from a tap, and water from 3 different companies, and did a taste test with people who claimed to drink bottled water as a preference.
By the end of the taste test, there was barely any difference between any of the different kinds of water and preference, and these were people who claimed to be very fond of bottled water, sometimes to the point where they refused to drink tapped water (fucking losers).
They also did laboratory tests on the different kinds of water, and found no real significant difference in how healthy each kind of water was. So, if you drink bottled because you think it's better for you, you've only become yet another chump to marketing and corporate propaganda.
That being said, I do buy bottled water occasionally. If there seems to be no water around aside from a bottled water machine, I'm not going to be a dumbass and refuse to pay a buck (or sometimes 2) if I'm dehydrated. I also buy a bottle of water every month or so. I drink the bottle, clean it, and refill it with tapped water until the bottle begins to look worn down, than buy another one.